1. Field of the Invention
The present invention relates to a projection control apparatus and a projection control method for controlling a projection apparatus.
2. Description of the Related Art
An example of a general method of controlling projection illuminance of a projection apparatus includes a system of changing display luminance of a projection device. To perform the control frame by frame, control of performing an operation in synchronization with a vertical synchronizing signal is necessary. Japanese Patent Laid-Open No. 2002-189458 (hereinafter, “Document 1”) realizes the frame-by-frame control of the display luminance by controlling the luminance of frame-by-frame images to display the images. Another method of controlling the projection illuminance of the projection apparatus includes a system of changing the luminance of a lighting optical unit (projection light source). Japanese Patent Laid-Open No. 2008-76611 (hereinafter, “Document 2”) describes a projector that changes the luminance of the lighting optical unit based on mode information indicating one of still image display and moving image display.
However, in an apparatus that needs to project only a desired frame unlike in a three dimensional measurement apparatus that needs to project a frame-by-frame video, the power is wasted in the conventional example in which the projection light source is continuously lit in each frame. In a projection apparatus used for three dimensional measurement, asynchronous control is performed when the control is not performed in frame synchronization. Therefore, real-time control cannot be performed, and redundant time is generated. The time prevents high-speed measurement. Video data is calculated to control frame-by-frame luminance in Document 1. However, frame-by-frame control cannot be performed using control information other than the video data. Therefore, the frame-by-frame control cannot be performed not only for a projection device, but also for other peripheral devices. In Document 2, the luminance of the light source is changed according to only the mode information unrelated to the frames.